The present invention relates to a holding device intended for monitors provided with displays, which device comprises an underbody and a carrier located above said underbody, on which carrier a monitor is applicable, the underbody and the carrierxe2x80x94which have front and rear endsxe2x80x94being interconnected via a mechanism that makes possible a readjustment of the monitor between different adjustment positions, and that comprises at least one link, which is connected with the underbody via a first joint that is placed at a comparatively short distance from the front end of the underbody, and with the carrier via an opposed second joint that is placed at a larger distance from the front end of the carrier, and which link is so arranged as to, at manual movement of the carrier relative to the underbody, forcedly guide the carrier plate between a rear end position, in which the front end of the carrier is situated near the underbody and the display of the monitor is oriented at a comparatively steep angle relative to a horizontal plane, and a front end position in which the carrier is pivoted upwards/frontwards relative to the underbody, in order to locate the display of the monitor at a flatter angle relative to the horizontal plane.
Working in computer offices is connected with ergonomical and physiological risks. In the long run people who work in a monotonous way during longer periods of time with a computer equipment placed on a desk or similar, accordingly run the risk of being affected by lesions in, e.g., wrists, arms and shoulders. A commonly occurring complaint in this context is the so-called mouse-arm. Lately, findings have appeared indicating that a better ergonomy is achieved if the work is performed with varying body postures, especially in that the operator alternately sits and stands during work. In this way, the body will inter alia utilize different muscle groups, primarily in connection with the handling of the control means of the computer and the manipulation of the different keys of the required keyboard.
In order to make possible working with a keyboard in a sitting body position as well as a standing body position, a keyboard holder has been developed that is the object of WO 98/23185. By means of this holder, the keyboard may quickly and easily be readjusted between a tipped-down, substantially horizontal state in which the keys and the control means may be manipulated in a sitting body position, and a tipped-up, angled state in which the same units may be manipulated in a standing body position with hanging arms, in which the arms and hands of the operator are to a large extent relaxed. By means of the keyboard holder disclosed in WO 98/23185, the problem with the keyboard work per se is solved in a satisfactory way. However, a problem arises with the monitor included in the computer equipment in connection with the changes of the operator between the sitting work position and the standing work position, more specifically due to the fact that not only the distance between the display of the monitor and the eyes of the operator, but also the angle between the display and the eyes is altered. Thus, in the sitting work position, the distance between the display and the eyes of the operator is comparatively short, at the same time as the display is adjusted at about right angles to the substantially horizontal sight-line of the eyes. When the operator gets up to the standing work position, the distance between the display and the eyes increases at the same time as the sight-line from the eyes downwards towards the display changes angles, more precisely in that the angle becomes smaller than 90xc2x0.
In order to solve the above-mentioned problems, different types of holding devices for monitors have previously been developed, having mechanisms that make possible a readjustment of the monitor between different adjustment positions. One type of such holding devices comprises a fastener and a carrier on which the monitor may be applied, and a pair of arms which via four joints are connected with the fastener and the carrier, respectively, in such a way that the carrier may be parallel-displaced vertically. In the construction is also included a spring that counterbalances the weight of the monitor in such a way that the monitor may be readjusted between different level positions and remain in given, desired positions as soon as the operator leaves hold of the monitor or its carrier. One example of this type of holding device is disclosed in GB 2 230 946. However, one disadvantage of such holding devices is that the display maintains its angle relative to the horizontal plane during the movement of the monitor between a lower end position and an upper end position. Another disadvantage is that the monitor in its upper end position is located at a rather high level above the appurtenant worktable; something that involves that the eye contact of the operator with the keyboard remaining on the worktable deteriorates.
A holding device of the type as defined in the preamble is previously disclosed in US 5 765 797. In this case, the underbody and a carrier plate for the monitor are interconnected via a central link, whose front end is connected to the underbody via a first joint placed near the front end of the underbody, and whose rear end is connected to the carrier plate via a second joint. At its rear end, the carrier plate is connected with the underbody via shaft, which at opposed ends is guided by side rails in the underbody and which serves as a third joint, around which the carrier plate may pivot, more specifically between a substantially horizontal tipped-down position and a position tipped up to about 50xc2x0. When pivoting the carrier plate from the tipped-down state to the tipped-up state, the rear edge of the carrier plate moves in a direction forwards along the underbody. The second joint that connects the carrier plate with the rear end of the link is placed about midway between the front and rear ends of the carrier plate, the length of the link, calculated as the distance between said first and second joints, being even somewhat larger than the distance between the second joint and the rear end of the carrier plate. In practice, this geometry of the known holder device brings about that the front edge of the carrier plate moves in an approximately vertical way from the tipped-down initial position to the tipped-up position, while the monitor moves upwards/backwards during the same manoeuvre. When the holding device is readjusted from the initial position, in which the user works in a sitting position, to the tipped-up position in order to permit working in a standing position, the distance between the user""s eyes and the display of the monitor will therefore gradually increase. In other words, the users""s conditions of working in an ergonomically purposeful way deteriorate when the carrier plate and the monitor are readjusted to the tipped-up state. Another disadvantage of the holding device according to U.S. Pat. No. 5,765,797 is that the fixed side rails require a deep building-in measure; something that renders the use of the holding device on shallow or narrow desks more difficult and requires an unnecessarily large surface on the desk.
The present invention aims at removing the above-mentioned disadvantages of the previously known holding devices for monitors and creating an improved holding device for the purpose of solving the operator""s problems with the monitor in connection with the alterations between sitting and standing work positions. Therefore, a primary object of the invention is to create a holding device, which during readjustment maintains the distance between the display of the monitor and the eyes of the operator, as well as the angle between the display and the sight-line of the eyes substantially intact. Still another object of the invention is to create a structurallly simple holding device that is compact vertically as well as depth-wise and which, therefore, requires a minimum of installation space. In a particular aspect, the invention aims at creating a holding device that has a minimal contact surface against the worktable; all this in order to make possible an optimal utilization of the table surface for storage purposes. Yet another purpose of the invention is to create a holding device that makes possible a readjustment of the monitor between different adjustment positions in a comfortable, effort-saving way by means of one single manipulation.
U.S. Pat. No. 4,706,920 discloses a holding device intended for monitors in the form of television sets, which device makes possible an angle readjustment of the monitor between a first end position, in which the display of the monitor is located near the vertical plane, i.e., is positioned at a steep angle relative to the horizontal plane, and a second end position, in which the angle to the vertical plane is larger. However, in this case the monitor moves backwards from its first end position towards its opposed end position; something that acts against its own purpose, since the distance between the display and the eyes of an observer increases when the obliquity angle of the display increases.
JP 111 49 255 discloses a device by means of which a monitor may be turned up to an active vertical position from a tipped-down, lying position. However, in this case the monitor is distanced from the observer when turning it up.